Inmolecular biology,elastase is anenzyme from the class ofproteases (peptidases) that break downproteins,[1] specifically one that can break downelastin. In other words, the name only refers to thesubstrate specificity (i.e. what proteins it can digest), not to any kind of evolutionary grouping.[2]
Eight humangenes exist for elastase:
| Family | Gene symbol | Protein name | EC number | ||
|---|---|---|---|---|---|
| Approved | Previous | Approved | Previous | ||
| chymotrypsin- like | CELA1 | ELA1 | chymotrypsin-like elastase family, member 1 | elastase 1, pancreatic | EC3.4.21.36 |
| CELA2A | ELA2A | chymotrypsin-like elastase family, member 2A | elastase 2A, pancreatic | EC3.4.21.71 | |
| CELA2B | ELA2B | chymotrypsin-like elastase family, member 2B | elastase 2B, pancreatic | EC3.4.21.71 | |
| CELA3A | ELA3A | chymotrypsin-like elastase family, member 3A | elastase 3A, pancreatic | EC3.4.21.70 | |
| CELA3B | ELA3B | chymotrypsin-like elastase family, member 3B | elastase 3B, pancreatic | EC3.4.21.70 | |
| chymotrypsin | CTRC | ELA4 | chymotrypsin C (caldecrin) | elastase 4 | EC3.4.21.2 |
| neutrophil | ELANE | ELA2 | neutrophil elastase | elastase 2 | EC3.4.21.37 |
| macrophage | MMP12 | HME | macrophage metalloelastase | macrophage elastase | EC3.4.24.65 |
The four "pancreatic elastases",chymotrypsin, and neutrophil elastase areserine proteases.[3] The "macrophage elastase" is amatrix metallopeptidase.
Chymotrypsin is weaker at digesting elastin than the architypical pancreatic elastase.[4]
Somebacteria (includingPseudomonas aeruginosa) also produce elastase; bacterial elestases work in many ways and includeserine proteases,aspartic proteases,thiol proteases, andmetalloenzymes.[2]
The fact that elastase can break downelastin in test tubes (while other proteases cannot) does not imply that there is a unifying function for all elastases in the living body. Instead, they each have their own role:
Elastases of theserine protease type preferentially break down peptide bonds on the carboxyl side of small, hydrophobic amino acids such asglycine,alanine, andvaline.
Elastase is inhibited by theacute-phase proteinα1-antitrypsin (A1AT), which binds almost irreversibly to the active site of elastase andtrypsin. A1AT is normally secreted by the liver cells into the serum.Alpha-1 antitrypsin deficiency (A1AD) leads to uninhibited destruction of elastic fibre by elastase; the main result isemphysema.
Therare diseasecyclic neutropenia (also called "cyclic hematopoeiesis") is anautosomal dominantgenetic disorder characterised by fluctuatingneutrophil granulocyte counts over 21-day periods. Duringneutropenia, patients are at risk forinfections. In 1999, this disease was linked to disorders in theELA-2 / ELANE gene.[10] Other forms of congenital neutropenia also appear to be linked to ELA-2 mutations.[citation needed]
Neutrophil elastase is responsible for the blistering inbullous pemphigoid, askin condition, in the presence ofantibodies. It may also play a role in the formation of abdominal aortic aneurysms (AAAs) and chronic obstructive pulmonary disease (COPD).
Elastase has been shown to disrupttight junctions, cause proteolytic damage to tissue, break downcytokines andalpha proteinase inhibitor, cleaveimmunoglobulin A and G (IgA,IgG), and cleave both C3bi, a component of thecomplement system, and CR1, areceptor onneutrophils for another complementmolecule involved inphagocytosis. The cleavage of IgA, IgG, C3bi, and CR1 contributes to a decrease of the ability of neutrophils to killbacteria by phagocytosis. Together, all these factors contribute to humanpathology.
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